Handling rigid sheet articles



A ril 13, 1965 c. R. DAVIDSON, JR. ETAL 3,178,045

HANDLING RIGID SHEET ARTICLES 14 Sheets-Sheet 1 INVENTORSS 694k: a. m /05mm? M Original Filed April 1 6, 1959 HANDLING RIGID SHEET ARTICLES Original Filed April 16, 1959 l4 Sheets-Sheet 2 FIG. 2

A free/v5) April 13, 1965 c. R. DAVIDSON, JR, ETAL HANDLING RIGID SHEET ARTICLES Original Filed April 16, 1959 14 Sheets-Sheet 3 FICA INVENTO S FIG. 3

A ril 13, 1965 c. R. DAVIDSON, JR, ETAL. 7

HANDLING RIGID SHEET ARTICLES Original Filed April 16, 1959 14 Sheets-Sheet 4 FIG] INVENTORS (mm-s ,e. mwosavJ/zfl W/tl/AM I? MIMI/AZ:

A TTOQNA'Y April 13, 1965 c. R. DAVIDSON, JR., ETAL 3, 8,0 5

HANDLING RIGID SHEET ARTICLES Original Filed April 16. 1959 14 Sheets-Sheet 5 mvmoRs amzzmm/wwie Mam/v P 01/157544 Mme/v5? April 13, 1965 C. R. DAVIDSON, JR., ETAL HANDLING RIGID SHEET ARTICLES Original Filed April 16, 1959 14 Sheets-Sheet 6 INVENTORS C/MRLCS IQBAV/DSO/VJQ W/LL/AM I? MITCHELL ATTOK/VE) April 1965 -c. R. DAVIDSON, JR., ETAL 3,178,045

HANDLING RIGID SHEET ARTICLES Criginal Filed April 16, 1959 14 Sheets-Sheet 7 FIG IO INVENTORS mwason/Je fi Owen's IE- WILL/AM P. MITCHELL BY A TO Q E) April 13, 1965 c. R. DAVIDSON, JR.. EI'AL. 3,178,045

HANDLING RIGID SHEET ARTICLES 14 Sheets-Sheet 8 Original Filed April 16, 1959 INVENTORS April 13, 1965 c. R. DAVIDSON, JR, ETAL 3,178,045

HANDLING RIGID SHEET ARTICLES 14 Sheets-Sheet 9 Original Filed April 16, 1959 INVENTORS amaze: z mwansmld W/lt/AM I? M/fCl/[ZL m 07. 8 UC Arm/PM?! A ril 13, 1965 c. R. DAVIDSON, JR, ETAL 3,178,045

HANDLING RIGID SHEET ARTICLES 14 Sheets-Sheet 10 Griginal Filed April 16, 1959 IN VENTORS amen: guy/050M1 1 BY mum MITCWA'ZL April 1965 c. R. DAVIDSON, JR., ETAL 3,178,045

HANDLING RIGID SHEET ARTICLES Original Filed April 16, 1959 14 Sheets-Sheet 11 FIG. ISA

(Amanda W11:

' {ml/4 e mrmaz Apr l 1965 c. R. DAVIDSON, JR., ETAL 3,178,045

HANDLING RIGID SHEET ARTICLES Original Filed April 16, 1959 14 Sheets5heet 12 FIG. I83

- (#4215: e. any/0:0 J? m By mu MM P Amt/mu April 13, 1965 c. DAVIDSON, JR. ETAL 3,178,045

HANDLING RIGID SHEET ARTICLES Original Filed April 16, 1959 14 Sheets-Sheet 14 252 2S3 79HZ F' IG. 18E

w C I f{ 1# 255 fi i R484 CH4- 256 {i534 257 j C118 I RS3-Z LEGENQ OF SYMQLS P8.| NORMALLY CLOSED PUSHBUTTON swn'cn 1 NORMALLY OPEN CONTACT 1H' NORMALLY CLOSED CONTACT NORMAN-Y OPEN CONTACT-CLOSES AFTER TIME DELAY T NORMAL-LY CLOSED CONTACT-OPENS AFTER TIME DELAY FIGJQ cm mm swn'cu R ELAY MOTOR STARTING CO".

TIME DELAY a: L

INVENTORS Omens 2. mr/mzwlei Y W MM P M/TC/IEAL i 1477' OQ VE' Y SOLENOID VALVES United States Patent Ofiice 3,l?8,h45 Patented Apr. 113, 1965 HANDLING RlGlID SHEET ARTICLES Charles R. Davidson, .lrn, Natrona Heights, and William P. Mitchell, Broolrliuc, Pa., assignors to Pittsburgh Plate Glass ompany, Pittsburgh, Pa, a corporation of Pennsylvania Original application Apr. 16, 1959, Ser. No. 3%,956. Divided and this application Jan. 15, 1952, Ser. No.

9 Claims. or. 214-39) This application relates to handling rigid sheet articles, and, while it has applicability in automatically loading rigid sheet articles into tongs and then unloading the articles after they have been transferred, the present invention has special utility in the automatic handling of various sizes of glass sheets precut to desired outlines and previously washed and dried so that they may be tempered and/or coated without requiring handling by a human hand.

Previous to the present invention, it had been necessary to manually load glass sheets in tongs before conveying the glass sheets through a lehr, where the glass sheets are heated to a temperature sufiiciently high for tempering by sudden chilling with air blasts or for forming metal oxide films by spraying suitable metal salt compositions, and then conveying the glass sheets through a quenching station where the heated glass sheets are suddenly chilled or through a spraying station where a suitable metal salt composition is sprayed onto the heated glass sheet surface. Also, prior to the present invention, glass sheets were removed manually from the grip imposed by the gripping tongs.

Many disadvantages are present in the former glass handling technique. First of all, manual loading unloading are quite expensive because of high labor costs. Secondly, manual handling causes shrinkage due to breakage. Thirdly, manual operations are not conducive to uniform treatment, a desideratum of mass production.

The present invention provides automatic handling of glass sheets that previously have been cut to outline, their edges abraded, their corners chamfered by steaming, and washed and dried. The benefits derived from the present invention will be understood better after studying the description of an illustrative embodiment of the invention which follows and which is made for the purpose of illustration rather than limitation. Reference to the latter may be obtained from studying the accompanying claims.

In the drawings forming part of the description of an illustrative embodiment.

FIG. 1 is a fragmentary longitudinal elevation of part of an illustrative embodiment of the present invention with emphasis on the automatic loading station and with certain parts unessential to understand the novel aspects of the invention omitted for clarity.

FlG. 2 is a longitudinal, fragmentary elevation of another part of the illustrative embodiment of the present invention with emphasis on the automatic unloading station and with portions removed to enable illustrating the important elements of the entire apparatus in two assembly drawings in sufficient detail to permit its understanding.

FIG. 3 is an enlarged fragmentary elevation of a pair of tongs specially constructed for use in the present invention for gripping glass sheets and particularly useful to secure automatic loading and unloading. larts of the carriage are removed to show the tongs in as large a scale as possible.

FIG. 4 is a fragmentary sectional view taken along the lines IVIV of FIG. 3.

FIG. 5 is a view similar to FIG. 4 showing only a portion of the structure of FIG. 4 and illustrating how the tongs are locked in position while receiving a glass sheet.

PEG. 6 is a fragmentary end elevation of a loading conveyor taken along the lines VIVI of FIG. 1.

FIG. 7 is a fragmentary sectional view of the pivotable conveyor section taken along the lines VII-VII of FIG. 1.

FIG. 8 is a longitudinal elevation of the glassloading station where glass sheets are automatically loaded into tongs.

FIG. 9 is a fragmentary end elevation of the glass loading station taken along lines IX-IX of FIG. 8 and omitting certain background structure to improve the clarity of the illustration.

FiG. 10 is a sectional view across a heating furnace taken along the lines X-X of FIG. 2. The furnace is used to heat glass sheets gripped by tongs.

FIG. 11 is a plan view of a quenching station where glass sheets are quenched after being heated in the furnace.

FIG. 12 is a fragmentary sectional view taken along the lines XlIXll of FIG. 2 and showing a fragmentary longitudinal elevation of a peg conveyor onto which glass sheets are deposited.

FIG. 13 is a fragmentary plan view of the peg conveyor.

FIG. 14 is an end elevation of a carriage lifting station where carriages are transferred to a return conveyor, taken along the lines XIVXIV of FIG. 2.

FIG. 15 is an enlarged fragmentary view taken at right angles to that of FIG. 14 along lines XVXV.

*lGURE 16 is fragmentary plan view of the system of drive mechanisms for forward movement of carriages and glass sheets.

FIG. 17 is a fragmentary plan view of the system of drive mechanisms for return movement of carriages.

FIGS. 18A through 18E are schematic electrical circuit diagrams of the control circuits for the apparatus depicted in the previous drawings.

FIG. 19 is a legend of symbols used in the electrical circuit diagrams.

General assembly Apparatus typifying the present invention utilizes a plurality of carriages C, (FIGURES l, 2, 3, 8, 10, 12, and 14) each provided with at least one bracket member 10 fixed to the bottom thereof. The bracket members (FIG- URE 3) each have an upper portion with a downwardly facing grooved surface 11 and a lower portion having an upwardly pointed member 12 of conical shape spaced below the grooved surface 11. A wedge shaped member 13 is constructed to have a pointed upper surface 14- and a comically grooved bottom surface 15, and arranged for vertical movement betwen an upper position wherein its upper pointed surface 1.4 locks into grooved surface 11 and a lowered position wherein its bottom conically recessed surface 15 pivots freely about pointed member 12. This free pivoting is possible because the conical recess of surface 15 has a larger apex angle than that of pointed member 12.

A pair of tongs T are pivoted with respect to each wedge-shaped member 13 and hang down therefrom. The tongs T include a stop member 15 pivoted to a common hinge pin 17 for the tong arms 18. The latter, in turn, are apertured near their bottom to receive opposed tong points 19 which are adapted to grip a glass sheet G therebetween, while additional extension arms 2t: extend horizontally outwardly of the upper extremities of the tong arms 18 to facilitate unloading as will be explained in greater detail later. Guide members 21, which insure that the glass is properly oriented into the tongs T on leading, are attached to the bottom of the tong arms 18. Tongs T also include a pair of upper links 5 pivoted to one another at their upper portions through a common link pin 6 carried by a clevis 7. The latter is rigidly attached to the wedge shaped member 13 through connector plates 8. Additional pins 9 serve to pivotally connect the bottom portion of one of the upper links to the upper portion of one of the tong arms 18 and the bottom portion of the other upper portion of the other tong arm 18.

Referring especially to FIGURES 1 and 2, an illustrative embodiment of the present invention comprises a conveyor extending along a longitudinal axis thereof and including in end-to-end relation along its length a first or loading conveyor LC, a pivotable conveyor section PC extending beyond the first or loading conveyor LC, and a downwardly slanted conveyor section DC. The first conveyor section LC extends from a cleaning station (not shown) and is constructed to convey clean glass sheets at an angle of degrees to the vertical (FIGURE 6). The loading conveyor section LC comprises a pulley P extending between rolls 22. The pulley P is driven by a motor The loading conveyor LC contains limit switches LS27 and L528 positioned for actuation by a glass sheet. The loading conveyor LC also includes idler rolls IR which support the bottom major surface of the glass sheets G while their bottom edge rests on pulley P.

The pivotable conveyor section PC is pivoted about a horizontal axis defined by a longitudinally extending Lpivot rod 24 (FIGURES l and 7) between an oblique plane aligned with the plane of glass support provided by the loading conveyor section LC and a vertical plane. Pivot rod 24 extends in a direction parallel to the longitudinal axis of the conveyor between support columns 25 and 33. Pivot rod 24 carries support structure for a pivotable conveyor drive motor 26 as well as structure supporting drive rolls 27. A piston and cylinder actuator 28 is pivoted between support column 25 and an arm 29 (FIGURE 7) rigidly attached to the pivotable conveyor section PC to cause pivotable conveyor section PC to pivot about an axis of rotation defined by the pivot rod 24. Free running rolls 30 are carried by the pivotable conveyor section'PC to balance a glass sheet in the interval between its removal from the loading con veyor section LC and its arrival at a loading station 31.

The pivotable conveyor section PC carries limit switches L829, L830, and L531, which are positioned for actuation by the leading edge of a glass sheet on the pivotable conveyor section PC. Other limit switches LSSZA and LSSZB are mounted on column 25 and are angularly offset with respect to each other by 15 degrees.

Fingers 32 extend downwardly from the pivotable conveyor section PC so that they actuate the limit switches LS32A and LS32B upon rotation of the pivotable conveyor section PC between a vertical and an oblique position. 7

The loading station 31 (FIGURES 1, 8, and 9) comprises the downwardly slanted conveyor section DC pivotable in a vertical plane. Conveyor section DC receives a glass sheet from the pivotable conveyor section PC when the pivotable conveyor section PC is tilted into alignment with the downwardly slanted conveyor section DC in a common vertical plane. Downwardly inclined conveyor section DC is pivoted in cantilever fashion between the vertical columns 33 of an open support structure, which includes horizontally extending beams 34 interconnecting columns 33 with vertical columns 35. One of. the vertical columns 33 also pivotally carries a piston cylinder whose piston rod 36 is pivoted atrits free extremity to the downwardly slanted conveyor section DC. The latter ends at a bumper wheel 37. Each column of the open support structure supports a vertically extending rack 38.

Pinion gears 39 mesh with racks 38 and are also keyed to axially aligned sectional shafts 47 which rigidly support opposed gripper members 40 at their inboard extremities. The sectional shafts 47 are mounted in 4 sliding and rotatable relation in bearings forming part of the hoist structure 41.

Gripper nembers 40 are axially movable relative to pinion gears 39 in response to axial movement of sectional shafts 47. The gripper members are made of a suitable glass facing material such as soft neoprene or rubber that does not mar glass.

Solenoids S1 and S2 are attached'to the longitudinal ex tremities of sectional shafts 47 removed from gripper members 40. Springs 4-2 are'connected from the solenoids S1 and S2 to a part fixed to the hoist 41 to urge gripper members at from each other non .ally. The action 05 the springs 42 is counteracted by thesolenoids Si and SZ, the details of which will be described later. The hoist 41 also includes wheels 43 which ride on tracks 44 fixed to the columns 35. Hoist 41 serves as support means for shafts 4?.

Guide wheels 45 are supported in freely rotatable rela tion to oblique supports disposed above downwardly slanted conveyor section DC to help support glass sheets in a vertical plane. The guide Wheels 35 and their support terminate short of the gripper .members 4th to permit the latter to move vertically while gripping a fiat sheet therebetween. A piston 46 actuates movement of the h-oist'l in a vertical path defined by the tracks 44.

Suitable control circuits and indexing means, which will be explained in detail below, control the sequence of operations of the various structural elements in this portion of the apparatus. Circuit details and operation will be described in greater detail below.

The control circuits which coordinate glass movements from downwardly slanting conveyor section DC to gripping engagement by tongs T are actuated by limit switches L833, L834, L835, L836, L837, and L333. Limit switch L833 is located in alignment with the plane of the glass sheets when downwardly slanted conveyor section DC is in its uppermost position and the sheets are supported by guide rolls 45. Limit switch L834 is positioned in the path of pivoting of the downwardly slanted conveyor section DC. Limit switches L535, L836, and L837 are mounted to one of the vertical columns 35 in the pathof movement of the hoist 41 and are constructed and arranged for actuation by the hoist at the uppermost iimit of the hoist movement, at a point intermediate the down-' Ward movement of the hoist and at the lowermost limit of hoist movement, respectively. Limit switch L533 is positioned for actuation by the downwardly slanting conveyor section DC when the latter is pivoted upwardly. Limit switches L334 and L538 are fixed to a bracket supported by one of the beams 34.

In order to insure that a straight edge of the glass sheet is disposed horizontally when the glass enters the tongs, the racks 38 and pinions 39 are so constructed that the pinion rotates slightly less than degrees, thereby rotating the glass sheet from a slightly downwardly inclined position into such position that the upper edge of the glass sheet occupies a horizontal line while the glass is still below its points of entry into the tongs. At this point, a hook 5t attached to the hoist 41 engages the bottom of the rack 38 and causes the latter to slide upwardly together with the remainder of the hoist structure without further rotating the pinion gear 39. Rack guides 56' are attached to column 35 to permit upward sliding of the rack 38 therethrough from its rest position on a stop.

A carriage conveyor CC provides a path substantially parallel to that of the glass conveyor sections LC, PC, and DC and comprises a high speed run-in carriage conveyor section 48 intermittently driven by a motor &9 for conveying a carriage from the loading station 31 into a tunnel-like furnace 51. A motor 53 (FIGURES 2 and 16) conveys the'carriages C through the furnace 51 along furnace section 52 of the carriage conveyor CC (FIG- URES l and 10). door 54 and an exit door 55.

The furnace also includes an entrance Limit switches 184%, L839, and L843 are located along the path of carriage movement for actuation by a carriage C as the carriage occupies various positions along carriage conveyor CC at loading station 31 and immediately outside the entrance door 54. Limit switches L841 and L842 are actuated by the opening and closing of en= trance door 54, respectively.

Furnace 51 comprises a plurality of interconnected fur= nace sections extending from the entrance door 54 to the exit door 55. As seen in the cross-sectional view of FIGURE 10, the furnace comprises a metal-reinforced refractory structure 56 that comprises one side wall 57, the roof 58, and part 59 of the other side Wall of the furnace.

The remainder 'of the other side wall of the furnace is provided by a laterally dis laceable metal-reinforced refractory structure 60 mounted on rollers 61 that travel along rails 62 extending laterally of the furnace. Sufficient structures as are provided along the length of furnace 51 to permit operating personnel to obtain access within the furnace for repair and maintenance work.

The inwardly facing walls of structures 55 and 6G support electrical heating elements 63, the thermal output of which is controlled by an individual control unit (not shown) for controlling the electrical power supplied to individual sets of heaters. The number and arrangement of heating circuits depends on the degree of control required for the radiant level longitudinally and transversely of the path of movement taken by the glass sheets through furnace Sl.

Carriage conveyor CC comprises stub rolls 64, which are continuously driven by motor 53 through a chain drive 65. The drive system also includes overrunning clutches 66, the employment of which will be described later.

Each carriage C contains a superstructure 67 that rides on the conveyor rolls 64, a connector 68 of -C-sl1aped construction and a bottom portion 69 which carries the tongs T. A lug or dog 67 is fixed to superstructure 67.

A positive instrument variable unit 70 contains cam limit switches CLl and CL2. The latter are rotated continuously by motor 53 to periodically actuate other elements by means which will be described in greater detail later.

Limit switch L866 is positioned along carriage conveyor CC for actuation by the carriages C within the furnace near exit door 55, while limit switch L845 is located for actuation by the carriages C just beyond the furnace 51. Limit switches L844 and L847 are positioned for actuation by the opening and closing of exit door 55, respectively.

Beyond the exit door 55 of furnace 51 is the quenching station 71, where the heated glass sheets are cooled rapidly upon leaving the furnace. At the quenching station 7i, opposed apertured blow boxes 72 are mounted on cams 73 and driven by motors 74 through suitable drive shafts and gearing so that the boxes 72 describe circular paths in planes parallel to the surfaces of the glass sheets held therebetween. A limit switch L846 is located along the path defined by the carriage conveyor CC for actuation by an oncoming carriage C to stop the carriage between the opposed blow boxes 72.

A compressor fan 75 forces air under pressure through ductwori: 76, including a flexible portion 77, into one of the blow boxes 72 so that air may be supplied under pressure through the nozzle orifices of the blow boxes 72. The other blow box 72 is similarly connected for circular orbital motion to driving means such as the earns 73, gearing, drive shafts and motor 74 and to another cornpressor 75 so that both surfaces of one or more glass sheets may be chilled equally rapidly at the quenching station 71. it is understood that a single driving means may be used to move both blow boxes and a single compressor may be used to supply quenching fluid under pressure to both blow boxes.

The carriage conveyor CC continues in a conveyor run-out section 78 driven by a run-out motor 7% (FIG- URES 2 and 16). The conveyor run-out section extends through the quenching station 71, an unloading station 8%, and ends at a carriage transfer station 81 at which the carriages C are removed from the terminal portion 82 of carriage conveyor CC. The control circuitry in sures that each carriage C is moved into proper registry with a peg conveyor 83 located below the area where the carriage conveyor passes between support posts $4, which are secured to the apparatus supporting structure.

Referring especially to FIGURES 2, l2, and 13, extension arms 29 are constructed and arranged for alignment with a pair of lifting arms 85, each int-erconnectin g levers 86 actuated by solenoids 83 and S4 to pivot relative to support posts 84 so that the lifting arms 85 move in substantially vertical paths flanking the vertical plane intersecting carriage conveyor CC into an upward position to lift extension arms 20 and cause tongs T to release their grip on the glass sheets. Springs 87 normally urge the levers 86 to pivot downwardly in spaced relation below extension arms 20 to provide clearance for an incoming glass laden carriage C, and also to permit the carriage C after unloading its glass sheet to continue along the terminal portion 82 of carriage conveyor CC to a carriage lifting station 81 (FIGURES 2, l4, and 15), where the carriages are lifted to a carriage return conveyor RC, which returns the carriages to the loading station 3-1 by way of a carriage lowering elevator 92 (FIGURE 1) and carriage conveyor CC.

Peg conveyor 83 (FIGURES 2, l2, and 13) extends transversely and obliquely downwardly from the unloading station 81 toward a packaging station (not shown) and comprises a sprocket wheel 93 driven through a peg conveyor clutch 94 by a peg conveyor drive motor 5. .One or more cooling fan units 96 overlie the peg conveyor 83, and a peg conveyor brake 97 is included to limit the movement of the peg conveyor 33. Pegs 98 are arranged in sets of three pegs, each set being aligned parallel to the sprocket wheel axis and the length of the carriage con veyor CC. Each set of pegs 98 is spaced suhiciently from its adjacent set to form a groove 99 to permit a glass sheet released by lifting levers 85 contacting horizontal extension arms 20 of tongs T to drop between adjacent sets of pegs.

Bumpers 83 have a length sufiicient to transverse two slats 89 of the peg conveyor, but are attached at one end only to provide support for the bottom edge of a glass sheet G deposited on the peg conveyor 83.

A screw jack 91 is pivotally mounted on one end of the peg conveyor 83 to adjust the height of the latter at its glass receiving end at unloading station 39 to accommodate for different sizes of glass sheets and to enable the apparatus to minimize the distance the glass sheet traverses as it falls freely from the tongs.

The cooling fan units 96 blow cooling air onto the surfaces of the glass sheets, thereby making it possible for personnel at the end of the peg conveyor 83 to remove glass sheets therefrom and package them.

Limit switch L843 is located along carriage conveyor CC for actuation by a carriage C and limit switch L849 along peg conveyor 83 for actuation by fingers 93A of a cam disc 93B rotatable with sprocket wheel d3. Circuits actuated by these limit switches insure that the movement of the peg conveyor 83 is correlated with that of carriages C along carriage conveyor CC.

The carriage lifting station 81 (FIGURES 2, l4, and 15) comprises a piston cylinder 1% pivotally supported at its bottom on a rigid support structure and containing a piston rod 1M secured at its upper end to a horizontal bar 1&2 forming part of a cradle 103 pivoted to cradle pivot supports 194-. A gear 1&5 is driven through gearing by a carriage transfer motor 106.

The cradle 103 includes a pair of arms 167 of equal length pivotally attached at their upper ends With respect to gear 105 through a gear shaft Hi8 and pivotally connected at their free ends to connecting lugs 10%. Another pair of arms 110 having a length equal to that of arms 167 is pivotally attached to a shaft 111 cradles relative to the gear shaft 158. The free end of each arm 11%? is also pivoted to a connecting lug 109. The latter extend outwardly to form fingers which move in paths in vertical planes between the conveyor rolls 64 in the carriage lifting station 81. A free running roller 109A is mounted on a bifurcated extension at the outer end of each lug 109.

A torsion spring 112 is mounted to surround shaft 108 and is constructed and arranged to react against downward motion of each arm 119. This prevents arms 110 from crossing relative to arms 107 and locking the system of arms 1tl7 and 115 and their lugs 109 during their downward rotational movement.

Movement of piston rod 101 causes the entire cradle 153 carrying the carriage transfer motor 1%, gear 105 and arm-s 157 and 110 to pivot about an axis defined by the cradle pivot supports 104. Carriage transfer motor 196 rotates gear 105 about gear shaft 108 to rotate arms 1G7 and 116 about their respective pivots. By correlating the movements of piston rod 1G1 with operation of the carriage transfer motor 106 and the position of carriage C along carriage conveyor CC and carriage return conveyor RC, carriages are removed fom the terminal portion 82 of carriage conveyor CC and deposited on the carriage return conveyor RC at carriage lifting station 81.

Limit switches L856, L851, L852, L853, L854, L855, L856, and L864 are located at the carriage lifting station 8 1 to insure a proper sequence of operations of the various carriage transfer elements. The cooperation of these limit switches will be discussed in detail below in connection with the electrical control system. However, for understanding the construction, the location of these car-riage lifting station limit switches will be described.

Limit switches L850 and L864 are located along the terminal portion 82 of carriage conveyor CC for actuation by a carriage C. Limit switches L851 and L853 are located for actuation by an actuating dog 51A fixed to cradle 103 as the latter moves during the transfer of a carriage C from carriage conveyor CC and carriage return conveyor RC. Limit switches L852 and L854 are fixed to cradle 1533 in position for actuation by a dog 155A fixed to gear 155. Limit switch L855 is located on the carriage return conveyor RC and positioned for actuation when a carriage C is deposited thereon. Limit switch L856 is located along carriage return conveyor RC for actuation by a carriage C passing therealong.

To complete the present general discussion, cradle 193 is so constructed and arranged that the rollers 109A of lugs 10? occupy position a slightly below the plane of support at terminal portion 82 of carriage conveyor CC to receive a carriage C. Rollers 159A move to position b when piston rod 101 is extended, thereby lifting the carriage C off the terminal portion 82 of the carriage conveyor CC in an upward arc a-b. Then, carriage transfer motor 1% rotates gear 105 in such a direction that the rollers 159A lift the carriage upwardly to position c in an upward arcuate path bc to a position slightly above the initial portion 113 of carriage return conveyor RC, which serves as the return run of carriage conveyor CC. Retraction of piston rod 161 moves rollers 189A from position 0 to position d in downward arcuate' path c-d. During this latter downward movement, the upper portion 67 of the carriage C is deposited on the rolls of the initial portion 113 of carriage return conveyor RC.

The carriage return conveyor RC is directly overhead of the carriage conveyor CC and includes the initial portion 113 located at the carriage lifting station and driven by a clutch drive 114. A retractable carriage stop 115 is located immediately before the terminal portion 116 of carriage return conveyor RC to contact lug 67 whenever it is necessary to stop carriage movement onto carriage lowering station 92. Terminal portion 116 is located at the upper portion of the carriage lowering station 92 where the carriages are transferred from the carriage return conveyor RC to the carriage conveyor 116 of carriage return conveyor RC for actuation by carriages C to control movement of carriages into the carriage lowering station 92.

The carriage lowering station 92 comprises a mechanism similar to the mechanism provided at the carriage lifting section 81, except that the sequence of steps followed during the carriage lowering operation causes the carriage support fingers to follow a cycle of arcuate move ments that is the reverse of the cycle followed by rollers 199A at the carriage lifting station. At the carriage lowering station 92 a cradle 119 is located. This cradle is similar in structure to that of cradle 193 at the carriage lifting station 81.

The sequence of positions occupied in a plane normal to the paths of movement of carriage conveyor CC and carriage return conveyor RC is dcbad, etc. at the carriage lowering station.

Limit switches L859, L865, L861, and L862 are located for actuation by structural elements of cradle 119 that returns a carriage C back into the portion of carriage conveyor CC at loading station 31 ready to receive some more flat glass for another cycle of operations. Limit switch L863 is located for actuation by a carriage C being deposited onto carriage conveyor CC, Where the carriage is again brought into the section controlled by limit switches L849, LC39, and L843, and the carriage is ready to resume another cycle.

Carriage drive and return drive system Referring to FIGURES l6 and 17, the various drives for the carriage conveyor CC and carriage return conveyor RC will now be described. I

Motor 53 which drives the furnace section 52 of carriage conveyor CC operates continuously through chain drive 65. lt'also continuously operates cam limit switches CL1 and CL2 of positive instrument variable unit through a chain drive 121.

Run-out section drive motor '7 9 drives the leading shaft 122 of carriage conveyor CC through a chain drive 123. Another chain drive 124 connects the remaining stub rolls of the terminal portion 82 of carriage conveyor CC to the leading shaft 122. Overrunning clutch 66 couples chain drive 124 into chain drive 65 and causes the latter chain drive to operate at the velocity of chain drive 124 Whenever the latter is actuated to a higher velocity than that normally attained by furnace conveyor section 52 controlled by motor 53.

Motor 53 drives shaft 125 through chain drive 135. Shaft 125 drives other stub rolls through chain drive 126 and also drives chain drive 127 which is coupled through an overriding clutch 128 to chain drive 65.

Motor 49 which controls the run-in section 48 of carriage conveyor CC operates shaft 129 through chain drive 130. The other rolls of conveyor section 48 are driven by shaft 125 through chain drive 131. An overrunning clutch 132 similar to clutch 66 is driven through shaft 129 by means of chain drive 133. Another overrunning clutch 134 interconnects chain drive 125 driven by motor 53 with a chain drive driven by motor 49.

. The overrunning clutches 66, 128, 132, and 134 are so constructed and arranged that the motors 49 and 79 control the speed of the carriage conveyor CC whenever they are imparting a velocity thereto in excess of the constant velocity provided by constantly running motor 53.

Motor 117, which operates continuously, actuates the carriage return conveyor RC through drive shaft 137 and chain drive 138. Clutch 114 is driven through drive shaft 139 and chain drives 138 and 14%) and, in turn, drives rollers 96 of the initial portion 113 of carriage return conveyor RC through chain drives 141 and 14-2 and shaft 143. In a similar manner, clutch 118 is driven by motor 117 through a reducer R and chain drives and drive shafts similar to those connecting the carriage return conveyor drive motor 117 to the clutch 114. In turn, clutch 118 operates the conveyor rolls 9d at the terminal portion 116 of carriage return conveyor RC through chain drives and drive shafts similarly arranged to those causing clutch 114 to operate carriage return conveyor rolls 9% at initial carriage return conveyor portion 113.

The cradle structure 103 transfers carriages from the carriage conveyor CC to the return conveyor RC, while the cradle structure 119 returns the carriages from the carriage return conveyor RC to the carriage conveyor CC.

Control circuitry and operation of apparatus A glass sheet traveling along loading conveyor LC closes normally open limit switch L528. If the position immediately ahead of the glass sheet is vacant, limit switch L827 remains open and nothing happens to circuit 185 containing relay R31. However, when a glass sheet occupies the position of limit switch L527 along loading conveyor LC and limit switch L528 is closed, relay R31 of circuit 185 is energized, since normally open contact LS27-1 of limit switch L527 is closed in circuit 185.

Simultaneously, normally closed contact LS27-2 of limit switch L527 is opened in circuit 186. This reversal of contacts for limit switch L527 causes a normally open contact R3l-1 of relay R31 (circuit 151)) which controls the high speed starter coil C23H of loading conveyor motor 23 to close and a normally closed contact R312 of relay R31 (circuit 151) which controls the low speed starter coil C23L of loading conveyor motor 23 to open. Thus, loading conveyor LC conveys the glass sheet at a high speed onto the pivotaole conveyor section PC until the glass sheet trailing edge moves beyond limit switch L528. This deenergizes relay R31 in circuit 185, thus permitting normally closed relay contact R312 in circuit 152 to close. This causes the low speed starter coil C23L of motor 23 to take over, thereby running loading conveyor LC at normal speed.

Speed of loading conveyor LC may also be controlled by closing normally open push button switch PB37 in circuit 150. Also, loading conveyor LC may be stopped altogether by opening normally closed push button switch PB36 which deenergizes motor 23 through circuits ESll through 153.

Pivotable conveyor section PC is inclined at 15 degrees from the vertical to receive the glass sheet coming otf loading conveyor LC. Therefore, the glass sheet is urged to contact normally open limit switch L529 in circuit 188, which closes, thus energizing relay R33, either through circuit 183 or circuit 189.

Relay R33 controls three contacts, R33-1, R33-2 and R33-3. Relay contact R331 (circuit 156) is normally closed, but opens when relay R33 is energized, thus stopping drive motor 26 for pivotable conveyor section PC. At the same time, normally open relay contact R33-2 (circuit 225) energizes solenoid valve SVZtlA which causes piston 28 to extend to pivot pivotable conveyor section PC from its oblique orientation in alignment with loading conveyor LC to a position in a vertical plane. The third contact R33-3, which is normally open, closes, preparing circuit 186 to respond to actuation of relay R32. The latter opens normally closed relay contact R321 (circuit 153) to cause loading conveyor LC to stop until pivotable conveyor section PC is clear of the preceding glass sheet.

Drive motor 26 for pivotable conveyor section PC is also controlled by a push button switch PB38 that is normally closed. P1338 controls the current flow through three parallel branches, one containing normally closed relay contactor R334 and an automatically gang op- 18 erated switch A6, and two additional parallel branches in series with a ganged manual control switch M5, one additional branch (circuit 154) containing normally open push button switch P1339 and the other branch (circuit 155) containing starter coil contact (126-1 for pivotable conveyor section motor coil C26.

Limit switch L539 is located adjacent limit switch L529 and is actuated simultaneously with limit switch L529. Thus, when a glass sheet passes limit switch L530, it causes normally open limit switch L530 to close, thereby actuating relay R34 through circuit 196.

Relay R34 controls normally open relay contact R34-1 in circuit 187 which is closed to prepare circuit 187 for closing of relay contact R324 to actuate relay R32. Relay R34 also opens normally closed relay contact R34-2 in circuit 226, and thus assures that the circuit controlling solenoid valve SVZUB is inoperative to retract piston 28 which tilts pivotable conveyor section PC from its vertical orientation to its slanted orientation while a glass sheet is moving from pivotable conveyor section PC to downwardly slanted conveyor section DC.

Normally open limit switch L831 in circuit 191 is in parallel with normally open limit switch 1831 in circuit 196). Thus, relay R34 is energized by a glass sheet contacting either limit switch L536 or L531 or both. Limit switch 1531 is located at the end of the pivotable conveyor section PC at a distance beyond limit switch L530 less than the length of a glass sheet G to insure that relay contact R342 is kept open until the glass sheet leaves the pivotable conveyor section PC entirely, at which time both limit switches L536 and L531 are in their normally open position, thus deenergizing relay R34.

When the size of glass sheets handled is to be changed, the position of limit switch L531 should be changed. Therefore, the position of limit switch L531 should he adjustable to enable the apparatus to be flexible in the size of materials it handles.

When pivot-able conveyor section PC starts pivoting into the vertical position, it actuates to close normally open limit switch LS32B in circuit 226. However, since the solenoid valve SVZtlB circuit also contains relay contact R342 which is maintained in the open position as long as a glass sheet contacts either limit switch L530 or limit switch L531 to keep relay R34 energized, solenoid valve SVZQB does not operate to retract piston 28 to tilt the pivotable conveyor section PC from its vertical position until after the glass sheet G is removed therefrom.

When pivotable conveyor section PC reaches its vertical position, it causes normally closed limit switch LS32A to open in circuit 189 to deenergize relay R33 in circuit 1.88. Relay R33 controls normally closed relay contact R334 in circuit 156, which was open while relay R33 remained energized. Upon closing, relay contact R33-1 actuates motor coil C26 of drive motor 26 of pivotable conveyor section PC.

With pivotable conveyor section PC occupied, both limit switches L530 and L531 are open, thus deenergizing relay Rdd through circuits 1.9%) and 191. Relay contact R3 14 in circuit 187 resumes its normally open position, thus dropping out relay R32 in circuit and acting as a holding circuit in case another glass sheet G has energized this latter circuit. At the same time relay contact 1134-2 in line 226 resumes its normally closed position to energize solenoid valve SVZtlB to actuate pivotable conveyor section PC into its oblique position.

Loading station controls When a glass sheet leaves pivotable conveyor section PC and enters the downwardly slanted conveyor section DC, it travels on the downwardly slanted conveyor section DC while supported between guide rolls 45 until it actuates limit svtu'tch L533, which closes to energize latching relay R351. in circuit 192.

Latching relay R35L controls four contacts. Normally open relay contact R354. in circuit 1S8 closes when latchglass sheet.

11 ing relay R35L is energized, thus preparing circuit 133 for actuating relay R33 when a glass sheet contacts and closes normally open limit switch L529.

Normally closed relay contact R352 is opened in circuit 189.

Normally open relay contact R353 closes in circuit 227 to energize solenoids S-1 and S2 which cause the gripper'members 40 to move axially toward each other with the inboard portion of compound shafts 47 to clamp against opposite surfaces of the glass sheet G.

Normally open relay contact R35-4 closes, thus energizing timer relay TRS in circuit 194. The timer relay TRS, which is normally open, closes to energize solenoid valve SV21A which retracts piston rod 36 to cause downward pivotal movement of the downwardly slanted conveyor section DC after a sufiicient time delay determined by the timer relay TR to permit the gripper members 40 to clamp the glass sheet G securely.

It is necessary to pivot downwardly slanted conveyor section DC in order to provide clearance for the subsequent upward movement of the hoist structure 41 which carries the gripper members 49 and the glass sheet.

Upon reaching its lowermost position, downwardly slanted conveyor section DC actuates limit switch L534. This latter actuation opens normally closed limit switch contact LS34-2 in circuit 228 to deenergize solenoid valve SV21A which operated to pivot downwardly slanted conveyor section DC.

At the same time, actuation of limit switch L834 closes normally open limit switch contact LS34-1 preparing circuit 230 to actuate solenoid valve SV22A when normally open limit switch L839 is contacted by a carriage C. This latter contact indicates that the carriage is in a position of proper alignment to receive a sheet of glass. Meanwhile, by closing limit switch LS39, circuit 248 is completed to stop coil 495 or motor 49.

Solenoid valve SV22A controls the extension of piston 46 which causes upward movement of hoist 41 along tracks 44. 'Movement of hoist 41 results in rotation of pinion gear 39 along rack 38 when actuated. Since the shafts 47 carrying gripper members 40 are splined to pinion gear 39 for axial movement relative to pinion gear 39, the gripper members 40 lift and rotate the glass sheets from the upper most position of downwardly slanted conveyor section DC into a position of predetermined orientation wherein the edge of the glass sheet formerly supported on downwardly slanted conveyor section DC becomes horizontally disposed as the upper edge of the glass sheet. Hood 50 makes contact with the bottom of rack 38, thus causing the racks 38 and pinion gears 39 to move upwardly without further rotation until the now upper horizontal glass sheet edge enters between and is gripped by tongs T. At this point, limit switch L535 is actuated by rack 38.

Limit switch L535 on actuation, opens normally closed limit switch contact LS352 in circuit 230 to deactivate solenoid valve SV22A, thereby stopping further extension of piston 46. This ends upward movement of the Actuation of limit switch L835 also closes normally open limit switch contact LS351 in circuit 195 to energize timer relay T R6.

Timer relay TRo controls three contacts. Contact TR61, which is normally open, closes circuit 195, which constitutes a holding circuit for timer relay TRtS, there by permitting circuit 1% to energize relay R35 when the hoist 41 descends a sufiicient distance to operate limit switch L836 on its downward movement following the step of loading a glass sheet onto the tongs T.

Another contact TR62, which is normally closed, opens on actuating timer relay TRS, thereby breaking circuit 227 to deenergize solenoids S1 and S2, thereby permitting the springs 42 to retract the gripper members 4%) from their glass gripping position. At the same time, contact TR6-3, which normally keeps circuit 231 open, is caused 12 solenoid valve SV22B, which retracts'piston 46 to actuate the downward movement of the hoist 41.

As the empty hoist 41 descends, it operates limit switch L836 to energize relay R36. Relay R36 closes normally open relay contact R36-1 in circuit 232 to prepare the furnace entrance door opening control circuit to actuate opening of the furnace door 54 when the downwardly moving hoist 41 is below the glass. It also opens normally closed relay contact R36-2 to deenergize solenoid valve SV23B in circuit 233 thus inhibiting the entrance door closing operation while the entrance door 54 is being opened through solenoid valve SV23A, and closes normally open relay contact R36-3 in circuit 197 to enable the latter to serve as a holding circuit for relay R36.

Hoist 41 continues to descend and at a predetermined time, can limit switch CL1 which is continuously rotated by carriage conveyor motor 53, operates to energize relay R37 in circuit 199. Cam limit switch CL1 is contained within positive instrument variable unit 70 and is adjustable to control its cycle of operation to coincide with movement of carriage C. Thus, when different lengths of glass are to be tempered, requiring different lengths of carriage, cam limit switch CL1 is adjusted accordingly.

When relay R37 is actuated, the following contacts are affected: 7

(1) Relay contact R371, which is normally open, closes to actuate solenoid valve SV23A in circuit 232', thereby causing furnace entrance door 54 to open, since solenoid valve SV23A actuates its opening.

(2) Normally closed relay contact R372 opens to hold open circuit 233 which controls the closing of entrance door 54 by means of solenoid valve SV23B.

(3) Normally open relay contact R37-3 closes in circuit 198 to provide a holding circuit for relay R37 in circuit 199.

(4) Normally closed relay contact R37-4 in circuit 230 opens to actuate stop coil 498 in circuit 248 to stop motor 49, since stop coil 498 on actuation, opens both normally closed contacts 498-1 in circuit 244 that con: trols high speed motor coil 431-1 and normally closed contact 498-2 in circuit 246 that controls the low speed motor coil 49L.

Entrance door 54 contacts limit switch L542 on opening, thus opening normally closed limit switch contact LS422 in circuit 232 to cut off power from solenoid valve SVZSA, thus stopping further opening of entrance door 54. At the same time, limit switch contact LS42-1 closes to prepare circuit 244 to energize high speed motor coil 43H to close normally open contact WET-1 in circuit 245 and to cause motor 49 to actuate conveyor section 48 to move a carriage rapidly into the furnace.

Meanwhile, exit door 55 closes limit switch L844v in circuit 249 to energize high speed coil 79H of the run-out conveyor section motor 73 to move a carriage C through exit door 55 at a high speed. Coil 73H also closes normally open contact 79H1 in circuit 250, which latter serves as a holding circuit.

A cam limit switch CL2 on power instrument variable unit 70 operates at the proper time to energize relay R42 in circuit 2% which closes normally open relay contact R42-1 in circuit 2%, which thereby serves as a holding circuit for relay R42. The later relay also closes relay contact R42-2 in circuit 244 in series with high speed L543, normally open limit switch contact LS431 in cir-' cuit 2% closes to energize relay R38 and normally closed limit switch contact LS43-2 in circuit 201. opens, deener ens re ay. R 

1. APPARATUS FOR LOADING RIGID SHEETS INTO TONGS COMPRISING: A FIRST CONVEYOR INCLUDING: A LOADING CONVEYOR SECTION CONSTRUCTED AND ARRANGED FOR CONVEYING FLAT RIGID SHEETS IN A TILTED POSITION, A PIVOTABLE CONVEYOR SECTION LOCATED IN END-TO-END RELATION TO SAID LOADING CONVEYOR SECTION AND PIVOTABLE BETWEEN A TILTED ORIENTATION ALIGNED WITH SAID LOADING CONVEYOR SECTION TO RECEIVE RIGID SHEETS THEREFROM AND A VERTICAL PLANE, MEANS OPERATIVELY CONNECTED TO SAID PIVOTABLE CONVEYOR SECTION TO PIVOT THE LATTER INTO A POSITION SUPPORTING A RIGID SHEET IN SAID VERTICAL PLANE, AND A RIGID SHEET RECEIVING STATION LOCATED IN ALIGNMENT WITH SAID PIVOTABLE CONVEYOR SECTION WHEN THE LATTER OCCUPIES SAID POSITION SUPPORTING A RIGID SHEET IN SAID VERTICAL PLANE, SECOND CONVEYOR MEANS FOR CONVEYING A TONG SUPPORTING CARRIAGE IN A CYCLIC PATH INCLUDING A LONGITUDINAL PATH PORTION DISPOSED ABOVE SAID RIGID SHEET RECEIVING STATION AND ADAPTED TO SUPPORT TONGS IN SAID VERCAL PLANE OCCUPIED BY SAID SHEET RECEIVING STATION, AND TRANSFER MEANS RESPONSIVE TO THE PRESENCE OF A GLASS SHEET AT SAID SHEET RECEIVING STATION AND A TONG SUPPORTING CARRIAGE IN ALIGNMENT THEREABOVE FOR LIFTING SAID RIGID SHEET OCCUPYING SAID SHEET RECEIVING STATION FROM SAID SHEET RECEIVING STATION AND INTO GRIPPING RELATION BY SAID TONGS. 